Many commercially available video conferencing systems only provide point-to-point video conferencing. Multipoint video conferencing uses an MCU (Multipoint Control Unit or conference unit). An MCU can operate either in a switched presence mode or continuous presence mode. In the switched presence mode, only one video stream is selected and transmitted to all of the participants based on either an audio signal or a “chairman” switch control. In continuous presence mode, the MCU receives video signals from each participant in a video conference, combines the signals to produce a single signal and sends the combined signal back to each participant. The combined signal enables each participant to view on one screen the pictures of the other participants along with his or her own picture on a real time basis using a split-screen. The sophisticated structure and large computation power of an MCU presently results in implementations of conventional MCUs on central servers. Some providers of MCU systems claim that their MCU software can be operated on a desktop personal computer. However, such MCU systems apparently support only the switched presence multipoint operation or produce a video stream in proprietary formats such that each participant installs special video conferencing software or apparatus.